The present invention relates to a method for the preparation of a resin membrane or, more particularly, to an efficient method for the preparation of a resin membrane useful as a pellicle covering a photolithographic mask in patterning of semiconductor devices, membrane for the separation of various kinds of gases, window material of optical instruments and the like having good uniformity in thickness.
Resin membranes used in the above mentioned applications or, in particular, those used as a pellicle in the manufacturing process of semiconductor devices usually have a thickness of 0.1 to 100 .mu.m and are conventionally prepared by the method including the steps of coating the surface of a substrate with a solution of the resin by using a spinner or spin coater to form a coating layer, drying the coating layer by evaporating the solvent to form a dry resin film on the substrate surface and peeling the resin film from the substrate surface.
The above mentioned coating method by using a spinner, however, has several problems and disadvantages. For example, the productivity of the method is necessarily low because the substrates must be coated one by one each time by mounting a single substrate on the spinner. In the method, namely, the substrate is rotated at a high speed and the resin solution is put before the start of or during rotation of the substrate so that the resin solution is spread over the surface of the substrate by the centrifugal force forming a thin layer of the resin solution having a uniform thickness on the substrate surface. Therefore, the method has a limitation on the size of the film to be obtained which is usually 200 mm to 300 mm or smaller in diameter in order to ensure good uniformity in the thickness of the membrane.